The present invention relates to a method for the alternate heating and cooling of a heat exchanger, such as a press or a reaction vessel, and also relates to a heating and cooling system in which the method can be carried out.
A method and apparatus for heating and cooling a heat exchanger of this type is, for instance, described in U.S. Pat. No. 3,556,201. Oil having a boiling point above the operating temperature of the apparatus is used as the liquid heat carrier. With certain additional costs, this known method can also be operated with liquid heat carriers the boiling point of which is below the maximum operating temperature, such as for instance, hot water.
Regardless of the type of liquid heat carrier, the capital costs for the heating and cooling apparatus are very high. With liquids having a high boiling point, such as oil, the large volume of the vessels, the armatures or fittings, the pumps, as well as the volume of the liquid itself, have a very strong tendencey to raise the costs. In addition, high-boiling liquids have only about fifty percent (50%) of the specific heat compared with water. When using water as the liquid heat carrier, the armatures, pumps and containers may be dimensioned somewhat smaller, but the necessary high operating pressure is disadvantageous as far as capital costs are concerned.
Aside from the capital costs for the heating and cooling apparatus for carrying out the above described known method, such method requires operating steps which are unsatisfactory regarding consumption of heat. The considerable volume of the liquid heat carrier is present in the passages of the heating plates of the press, the distributers, hoses and connecting pipes, which volume has to be heated and cooled just like the heating plates. A similar amount is present in the feeding and discharging pipes of the circulating pump and the reversing armatures. The mass of steel for this portion of the apparatus must likewise be heated and cooled. In addition, a considerable amount of electrical energy is required for pumping the heat carrier.
It is an object of the present invention to provide a method of heating and cooling a heat exchanger alternately, which has a considerably lower energy consumption compared with heretofore known methods of this type. It is also an object of the present invention to lower the capital costs for the heating and cooling apparatus for carrying out the method according to the present invention.